Electric circuit breaker



P 4 w. G. HARLOW ET AL 2,399,435

ELECTRIC CIRCUIT BREAKER Filed Dec. 26, 1942 l 2 Sheets-Sheet 1 lllmIll: unwunulM Inv wi ton Haw-low, George A Hem-s.

h- Attorney- April 1946- w. s. HARLOW ETAL 2,399,485

ELECTRIC CIRCUIT BREAKER Filed Dec. 26, 1942 2 Sheets-Sheet 2IYlVeYTbOTS; Winton G. Harlow, George A. Healis,

T ein Attorney.

menus Apr. so, 1946 naac'rmc cracurr mama Winton G. Harlow, Upper Darby,and George A. 'Healis, Lansdowne, Pa., assignors to General ElectricCompany, a corporation of New York Application December 20, 1942, SerialNo. 470,264 '1 Claims. (01. zoo-14a).

Our invention relates to electric circuit breakers, more particularly toair circuit breakers of the load-break disconnecting switch type for anintermediate voltage rating. such as 15,000 volts, capable ofinterrupting and efficiently clearing load power circuits, and has forits principal ob- .iect the provision of an improved circuit breaker ofthe aforesaid type that is compact and rugged in construction, reliableand fast in operation,

and that is capable of clearing medium voltagepower circuits over a widerange of load including minimum values of current.

Our invention will be more fully set forth in the following descriptionreferring to the accompanying drawings, and the features of noveltywhich characterize our invention will be pointed out with particularityin the claims annexed to and forming a part of this specification.

Referring to the drawings, Fig. 1 is an elevational view, partly insection. of an air circuit breaker embodying the present invention inthe currents,

' closed circuit position thereof; Fig. 2 is an elevational view, partlyin section, of the contact structure of the circuit breaker shown inFig. 1 in an initial stage of the circuit opening operation; Fig. 3 is asimilar view showing the breaker in a more advanced stage of the openingoperation; Fig. 4 is a similar view showing the breaker in an opencircuit position, and Fig. 5 is a similar view showing the breaker in apartially closed circuit position.

The air circuit breaker shown in Fig. l is adapted both to interruptload currents (as well as low amperage magnetizing currents), and todisconnect the circuit generally in the manner of the air breakdisconnecting switch. The circuit breaker comprises a pair of relativelyfixed terminals indicated at l and 2 arranged to be interconnected inthe normal closed circuit position by a main current-carrying contactmember I. The contact member 3 is formed as a double blade contact thatis secured to and mounted on a rotatable insulating shaft 4 for pivotalmovement with respect to the upper fixed terminal I. An operating handle5 is connected 45 to the insulating shaft 4 for rotating the same andcausing the blade I to move toward and away from the fixed terminal I.

The upper terminal I has connected thereto a fixed contact structureincluding an arcing contact and main current-carrying finger-typecontacts I arranged to be engaged by the blade 3 (Fig. Also mounted onthe fixed terminal is an arc extinguishing structure 8 comprising in thespecific instance a narrow arc chute of a suitable type hereinafterdescribed. The arcing contact 8 is mounted within the arc chute forcoaction with an arcing contact I that is pivotally mounted on andcarried by the main blade at "I, whereas the main current contacts I aredisposed exteriorly of the arc chute at opposite sides thereof as alsoindicated by Fig. 5.

The arcing space or chamber within the arc chute comprises a narrow slotII that is open at the lower end of the chute, for operation of thearcing contact land also at the upper end at l2 for venting the arcgases. Th sides of the arc chute are substantially closed and the mainpart of the are chute is provided with are extinguishing baiiiestructure indicated at It for cooling, lengthening and attenuating thearc stream as it moves upward into the chute. This movement of the arcis facilitated by arcing horns located at opposite ends of the arcchute; one of which is conveniently formed by the fixed arcing contact 8and the other at I 4 being close to the path of the arcing tip 0a of thearcing contact. However, our invention is not limited to a specific formof arc chute and further description thereof is unnecessary other thanto point out that the chute may be of the interleaving baiile typedisclosed in Letters Patent to L. J. Linde, No. 2,293,513 issued August18, 1942 for Electric air circuit breaker. Also a mufller for the chutmay be used if desired according to the above patent for increasing thecurrent interrupting capacity.

The arcing contact is operatively related to the main blade so that whenthe handle 5 is rotated as clockwise from theposition shown in Fig. 1 toopen the circuit breaker, the main contacts at 3 and I first partcontact and move a predetermined distance toward open circuit positionbefore parting oi the arcing contacts occurs at 1 40, 6 and 9. Since thearcing contact 9 is electrically connected to the blade 3 the circuitbetween the terminals will be opened .at the arcing contacts rather thanat the main contacts so that the arc to be extinguished is drawn withinthe chute 8 -where it attaches to the arcing horns and is extinguishedas it moves into the baiile structure.

To this end the arcing contact 8 is latched so that it does notimmediately or completely follow the blade until the blade reaches acertain position whereupon the latch is tripped by means associated withthe blade and spring biasing means, that is stressed during the initialmovement of the blade, snaps the arcing contact away from its fixedcontact 6. Coincident with this operation a strong Jet of air isdirected substantially transversely of the arc stream at the arcingcontact so as to drive the arc upward within the chute, thereby tofacilitate the interruption of large as well as small current arcs.

Specifically, the above results are brought about by providing thearcing contact with a latching tgg1e. l5-l8 that is arranged to beoverset, as shown in Fig. 1, and resiliently held in said position by anovercenter spring H. The upper end of the toggle link I! is providedwith a pin it guided for limited vertical reciprocal movement in a slotlab formed in a lug Isa secured with respect to the arcing contact 9.The pin l8 also carries a roller 69 oilset so as to be in alignment witha fixed catch 20 (and n upward into the arc chute so as to traverse thealso a second fixed catch a) secured to the lower part of the arc chutealong an edge thereof. The lower toggle link it is connected to a guidelink 2! that is pivotally connected at 22 to the arcing contact andbiased by a spring 23 in counterclockwise direction so as normally tohold the latching toggle ib-IB as a unit in its upper latching position.

For the purpose of controlling the latching toggle and for directing anair jet upward into the chute when the arcing contact is opened, apneumatic device comprising a cylinder 24 and a piston 26 is operativelyconnected to the arcing and blade contacts. In the specific arrangementshown the cylinder 24, which is provided with an air jet nozzle 26, ismounted on and secured to the arcing contact 9 and coacts with thepiston connected through its operating rod 21 to an offset portion ofthe main blade 3 at 28. The piston rod 21 clears the toggle but anadjustable extension 29 carried by the piston is arranged so as to besubstantially in alignment with the knee or central pivot 30 of thetoggle. The toggle is held in the overset position shown in Fig. 1 bythe spring i1 and a stop pin 3| that is arranged to be engaged by anextension of the link l8. Accordingly, when the knee of the toggle ismoved sufficiently over center toward the right the spring I! causescollapse of the toggle so that the roller l9 moves downward in the slotI917 sufilciently to clear both the catch 20 and the catch 20a.

The operation of the circuit breaker is as follows: Assuming that thecircuit breaker is in the closed circuit position shown in Fig. 1, the

.opening operation is performed by rotating the handle 5 clockwise so asto open the circuit at the upper terminal I. During the initial openingmovement of the main blade 3, the arcing contact 9 remains in slidingengagement with the fixed contact 6. Before the arcing contact 9 movesaway from the fixed contact, however, the toggle latch roller l9 hasengaged the fixed catch 20 as clearly shown by Fig. 2. Since the toggleis still locked in its overset position further immediate movement ofthe arcing contact is restrained. The blade 3 continues to moveclockwise stressing the arcing contact spring 9b and drawing with it thepiston 25 which, incidentally, is thereby positioned within the cylinder24 in readiness for a working stroke, i. e., a jet producing stroke.

As the blade 3 reaches a predetermined position in its opening strokewhere it is safe to open the arcing contact without danger of the arerestriking to the main blade, the piston extension 29 engages the kneeof the toggle and causes it to collapse as illustrated in Fig. 3. As thetoggle collapses under influence of the spring I! the latching roller l9moves beneath the fixed catch 2|! so as to release the arcing contact.Thereupare stream. at the arcing contact and force the arc upward alongthe arcing horns into the chute structure where it is extinguished. Itwill be noted, referring to Fig. 4, that the piston 26 closes off thenozzle opening 28 near the end of the working stroke. The trapped air atthe left end of the cylinder therefore serves to cushion the openingshock of the arcing contact. Further opening movement or the breakercauses the arcing and blade contacts to move as a unit as indicated byFig. 4 to the complete open circuit disconnecting position wherein theblade unit is in substantially horizontal position.

It will be noted that relative movement 0. the cylinder and piston fromthe position of Fig. 3 to that of Fig. 4 also causes resetting of thelatching toggle to the original overset position shown by Fig. 1.Accordingly, when the circuit breaker is to be closed, counterclockwisemovement of the handle 5 moves the reset contacts and pneumatic deviceas a unit as shown by Fig. 5 toward the closed circuit position. It willalso be noted that toggle latch roller l8 during closing is forceddownward by the cam-like surfaces at the rear of the fixed catch 20 anda second catch 20a. This movement of the toggle roller while the latchremains in its locked or overset position is made possible by theresiliently biased guide link 2| that permits the toggle to movedownward as a unit as the roller l9 rides along the cam surfaces.Accordingly the blade unit can be moved without interference from thelatching toggle to the fully closed circuit position shown in Fig. 1, inwhich position the spring 22 of the toggle guide link holds the toggleup behind the fixed catch 20.

The closing duty, as well as the opening duty, falls on the arcingcontacts which close just prior to closing of the main contacts. Inclosing the breaker on a relatively high voltage circuit, an arc may beestablished at the arcing contacts before the contacts actually toucheach other and before the roller l9 engages'the fixed catch 2!. In orderto insure correct operation of the pneumatic device in case the switchis partially closed to a position where arcing would occur and thenreopened, the second fixed catch 20:: is provided. The location of thiscatch is such that it is engaged by the roller is before an arc can beestablished during a closing stroke. Accordingly, an extinguishing jetof air is directed from the pneumatic device when the latching toggle istripped at the second catch 20a.

It should be understood that our invention is not limited to specificdetails of construction and arrangement thereof herein illustrated, andthat changes and modifications may occur to one skilled in the artwithout departing from the spirit of our invention. I

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. An electric circuit breaker comprising a pivotally mounted maincontact blade, a relatively fixed coacting contact, an arcing contactpivot-' ally mounted on said blade and movable with respect to both saidfixed and main contacts. spring means ior biasing said arcing contactaway from said fixed contact and toward said blade during a circuitopening operation, latching means including a toggle for said arcingcontact arranged to engage a-fixed part of said breaker for holding saidarcing contact in engagement with said fixed contact during the initialcircuit opening movement of said main contact blade, means associatedwith said blade for tripping said toggle and releasing said arcingcontact, and a pneumatic device including a cylinder mounted on saidarcing contact and a piston connected to said blade operated by saidspring means and arranged to direct an arc extinguishing jet of airtoward the arc stream in accordance with unlatching and opening movementof said arcing contact. 1

2. An electric circuit breaker comprising a pivoted main contact blade,a relatively fixed meeting contact, an arcing contact pivotally mountedon said main contact blade, spring means for biasing said arcing contactaway from-said fixed contact alongside said blade, latching means forholding said arcing contact in engagement with said fi'xed contactduring the initial circuit opening movement of said blade, said latchingmeans arranged to be tripped by and in accordance with predeterminedopening movement of said blade. a piston and cylinder associated withsaid arcing contact and blade arranged to direct an are extinguishingjet of air toward the arc stream in accordance with unlatching andopening movement oi. said arcing contact, and means connected to saidpiston for tripping said latching means after a predetermined openingmovement of said blade.

8.'An electric air circuit breaker comprising a pivotally mounted maincontact blade, a relatively fixed coacting contact, an arcing contactpivotally mounted and movable with respect to both said fixed and maincontacts, spring means for biasing said amino: contact away from saidfixed contact and toward said blade, latching means including a togglefor said arcing contact arranged to be overset to engage a fixed part ofsaid breaker for holding said arcing contact in engagement with saidfixed contact during the initial circuit opening movement of said maincontact blade, and means associated with said blade for tripping saidtoggle and releasing said arcing contact.

'4. An electric air circuit breaker comprising a pivotally mounted maincontact blade, a relatively fixed coacting contact, an arcing contactmovable with respect to both said fixed and main contacts, spring meansfor biasing said arcing contact away from said fixed contact and towardsaid blade. latching means including a toggle for said arcing contactarranged to be overset to engage a fixed part of said breaker forholding said arcing contact in engagement with said fixed contact duringthe initial circuit opening movement of said main contact blade, meansassociated with said blade for tripping said toggle and releasing saidarcing cortact, and a pneumatic device including ecyiinder and pistonoperativeiy related to both said arcing and blade contacts so that theinitial opening movement of said blade. sets said device in readinessfor operation, said device being bperated by said spring means upontripping of said toggle for directing an arc extinguishing jet of airtoward the arc stream at said arcing contact.

5. An electric air circuit breaker comprising a pivotally mounted maincontact blade, a relatively fixed coacting contact, an arcing contactmovable with respect to both said fixed and main contacts, spring meansfor biasing said arcing contact away from said fixed contact, a latchingtoggle connected to said arcing contact arranged to engage a relativelyfixed catch for holding said arcing contact in engagement with saidfixed contact during the initial circuit opening movement of said maincontact blade, means associated with said blade for tripping said toggleand releasing said arcing contact, a pneumatic device operable by saidspring means in accordance with relative movement between said arcingand blade contacts after said tripping operation, said device arrangedthereupon to direct an arc extinguishing jet of air toward the arcstream at said arcing contact means for resetting said latching toggleprior to the closing operation, and a second relatively fixed catcharranged to be engaged by said toggle during closing for causingoperation of said pneumatic device upon partial closing and reopening ofsaid arcing contact.

6. An electric air circuit breaker comprising a pivotally mounted maincontact blade, a relatively fixed coacting contact, an arcing contactmovable with respect to both said fixed and main contacts, spring meansfor biasing said arcing contact away from said fixed contact, a latchingtoggle connected to said arcing contact arranged to engage a fixed catchon said breaker for holding said arcing contact in engagement with saidfixed contact during the initial circuit opening movement of said maincontact blade, means resiliently biasing said toggle towards itslatching position, means associated with said blade for tripping saidtoggle and releasing said arcing contact, said releasing operationcausing resetting of said toggle, a pneumatic device operated by saidspring means in accordance with said releasing operation for directingan arc extinguishing jet of air toward the arc stream at said arcingcontact, and a second fixed catch arranged to be engaged by said togglewhen said arcing contact is in a partially closed position, said secondcatch causing tripping of said toggle and release of said arcing contactto operate said pneumatic device when said breaker is reopened beiorecomplete closure.

'7. An electric air circuit breaker comprising a movable main member, arelatively fixed contact. an arcing contact movable with respect to bothsaid fixed and main members, means for biasing said arcing contact awayfrom said fixed contact, means for holding said arcing contact inengagement with said fixed contact during the initial opening movementof said main member, and a pneumatic device connected to saidarcing'con- WINTON G. HARLOW. GEORGE A. M.

